Preserving wood.



W.' BUEHLER.

PRESERVING WOOD- APPLICATION FILED JUNE 6, 1908.

Patented Sept. 22, 1908 NITED: T TES- PATENT oFrIoE.

WALTER BUEHLER, or

MINNEAPOLIS, MINNESOTA, AssIeNoR or ONE-HALF TO GEORGE w.

.BESTOR, or MINNEAPOLIS, MINNESOTA.

.Pnnsnnvme woon.

To all it may concern: i Be it known'that I, WALTER BUEIILER, a'

citizen of't'h'e United States, and resident of preserves the wood against Minneapolis,- Minnesota, have invented certain new and useful Improvements in the Art of Preserving Wood, of which the following is a full, clear, and exact description, such-as will enable others to practice the same.

My invention relates to improvements in the art of impregnating wood with preserva tiveli uids. i

Whi e not limited thereto the invention is chiefly concerned with the impregnation of seasoned wood withjbituminous liquids and distillates of bituminous substances, commonly known as oils, which are substantially free from water, such as creosote oil.

It is now generally conceded that, when properly treated with creosote oil, a seasoned stic retains substantially its maximum strength as the oil, unlike water, does not enter or weaken the wood fiber; also the durability of the wood is greatlyenhanced, by reason of the fact that pying the cells and pores of the Wood, -exeludes moisture from the wood. fiber and retards and practically prevents the decom sition or rotting thereof and also efiectua ly the attack ofeither land or marine insects. The object of my invention is to enable the eflectual preservation of wood by impregnation with. preservative liquid, preferably creosote, and to accomplish the desired results and effects without detriment to the wood fiber, within a short space of time and atlowcost. r i My invention'comprises a process, or improvement in the art, of preserving seasoned or partially seasoned wood, which consists in first exhausting the gaseouscontent of the wood, principally. air, and thus creating .a vacuum in the wood cells and pores, then immersing the wood in preservative liquid, then by pressure upon the liquid driving the requisite quantity thereof into the cells and pores o i. e. withdrawing the surplus liquid, then sub jecting the artially impregnated wood to the action 0 compressed gas, preferabl air, thereby driving the liquidinto the woof and "then relieving the gas pressure.

stood by reference to the or receptacle of the the creosote oil, occuthe wood, then emersing the wood,

together with certain desirable incidental steps. thereof will be more readily underaccompanying drawmg, forming a art of this specification and in which I have lustrated the ap aratus that. I have found to be best adapte to the purposes of the invention. '1

In these drawings, 2, represents a cylinder kind usually employed in preserving wood. This enough to contain a car or truck, 3, and its load of-wood, 4. A large door or head, 5, tightly closes the end of the cylinder, the packing being such as to permit a high pressureof liquid or of gas to be maintained in the cylinder. The dotted lines, 6, represent a steam coil which may be and is preferably located within the cylinder. 7

7 re resents a liquid reservoir of capacity excee vided with an indicator, 8, for dete the quantity of liquid in or that is withdrawn from the reservoir. I

The dotted lines, 9, represent a steam coil which maybe and preferably is located inthe reservoir, 7

When creosote oil is used it is usually necessary to heat or warm it, in order to keep it in a'liquid state, its tem erature of liquefaction approximating 150 egrees Fahrenheit. pipe or main,.10,- connects the reservoir with the cylinder, 2, branches, 10 and 10", being preferably employed at the cylinder. A pump, 1 1, is used for transferring the liquid from one receptacle to the other and is also referably used in obtaining the necessary uid 'ressure within the cylinder. Suit ab e va ves, -12,' 13and 14 are arranged in the connections, 10, 10', 10". Asmall boiler, 15, supplies the steam required in the coils, 6 and 9 and is connected therewith by pipes containing the va1ves,. 15', 6' and 9. i d 16 is the blow-luff connectionof the cylinpump, 17,'is connected with the cylinder by a pipe, 17, containing the controllingvalve, 17".

18 represents apparatus for compressing and storing air or other gas for use in the cylinder, being connected therewith by pipe,

18-, provided with controlling valve, 18".

19 1s a vacuum gage, and 20, a ressure gage, both connected with the cylin or.

Patented Sept. e2, 1908. V

cylinder Is large mg that'of the cylinder, 2, and procontaining a valve, 16. A vacuum ment that the cylinder is'completely filled 1 gas in My novel process is performed or carried out as follows: Upon the arrival of a load of substantially dry or seasoned wood at the cylinder, the door, 5, thereof is swung open, the loaded car is laced in the cylinder and the door is tight y closed. Meantime the valves, 12, 14, 18" and 16 are closed,-to completely closeor seal the. cylinder. At

such time the cylinder is free from liquid, the

same having been drained therefrom prior to the opening of the cylinder. After the cylinder is closed the vacuum pump, 17, is started and the vacuum valve, 17, opened to establish communication between the pump and the cylinder. The air is thus removed from the cylinder and, slowly from the wood therein, until a considerable vacuum, usually approximating 20 to 26 inches, is established throughout the wood. This state is readily ascertained by closing the valve, 17", when, if the vacuum gage remains substantially stationary, it indicates that aproper rarefaction has been effected. In this manner the wood is deprived of air and vapors and the cells and pores previously emptied of mois ture and sap by the seasoning processare preparedto receive the preserving liquid.

Thenext ste of the process consists in filling the, cylin er with liquid from the reservoir, 7. In case the preferred preservative, creosote, is used, it is warmed and liquefied before introduction to the cylinder and when found necessary the body of liquid in the cylinder is kept warm by steam in the coil,

6, though preferably no attempt is made to raise the temperature of the reserving liquid above that at which it lique es. The ump, 11, is preferably used in filling thecy der with liquid and I prefer to continue the vacuum pump in operation until the liquid rises to the to of the cylinder; the vacuum valve, 17", ist en closed,

The operation of the vacuum pump during the of the tank is not essential to the success of the process, though desirable, as otherwise the slow destruction of the vacuum by the entrance of the liquid results inslight non-uniformity of the liquid charge in the timbers in the u per and lower part of the cylinder. The 'iference is not important, but as intimated may be avoided by maintaining the vacuum during the filling operation. 0r a small uantity of air'may be admitted'to the cylin or to reduce the vacuum prior to the entrance of the liquid, this last,

expedient, however, is objectionable as tending to recharge the timber with air.

The pressure llIIlp, 11, is continued in operation after t e cylinder has been filled andis kept in motion until the indicator, 8, shows that the re uisite quantity of preservative has been 'orced into the cells and pores otthe wood in the cylinder. A readis taken'from the indicator, 8, at the moseaesc and further movement of the indicator therefore shows the quantity of liquid that is placed in the Wood. A liquid pressure approximating one hundred to one hundred and fifty pounds is usually sufiicient to drive the charge of liquid into the wood. Being unopposed by air, vapors or liquids within the cells of the wood, the preserving liquid very quickly penetrates the outer pores and cells and the time consumed in thus charging the timber is shorter than in other processes. In actual practice of my prrocess, the period of liquid pressure varies om thirty minutes to anhour or more, according to the character and size of the wood under treatment.

When the indicator, 8, shows that the required amount of ii uid has been lodged in the wood, the pump 1s reversed and the surplus liquid is drained from the cylinder, until the wood is completely emersed. If desired, the .valve, 12, may be opened at this time and the .operation of the pump supplemented by admitting compressed air to the cylinder.

After withdrawing the surplus liquid from the cylinder, I close the valves, 12 and 14 (all other valves are then closed) and admit gas under pressure from the source, 18. The gas employed is preferably air at normal temperature, in other words cool, and I prefer that the pressure of air in the cylinder shall not exceed twenty-five pounds. This pressure may be maintained either continuously or intermittently by manipulation of the valve, 18".. The compressed air penetrates the pores and cells of the wood in the cylinder and ultimately forces the charges of liquid therein further into the sticks, thus distributing the liquid uniformly upon the walls of the cells and pores throughout the wood. In this manner a relatively small uantity of preserving liquid is distributed t roughout the cellular structure, forming thereon films which effectually exclude moisture from the wood fiber, thus retaining the full strength of thecwood. In practice the air pressure is continued until gaseous equilibrium is established in the wood, .a fact' indicated by the hand of the pressure gage remaining stationary when the compressed air valve, 18", is closed. 7 In using creosote, I have noted that the temperature of the wood following the charge of warm li uid is sufiicient'to maintain the creosote in 'quid condition in the pores and cells long enough to ermit the inward distribution of the liquid by the compressed air, but in extremely cold weather, it is sometimes necessary to slightly warm the cylinder to prevent the premature solidificatron of the creosote in the outer pores of the wood.

My reference for the low pressure air or dicate d above is based upon the fact stantially as descri that air or gas at twenty-' fivepounds pres temperature, thereby-lodging a quantity .01

sure will quletly flow from: the. wood when the latter ls-removed-from the cylinder Without ex ellin the liquid from the cells and pores t moi. Under high pressure the sudden return of the wood to atmospheric pressure is usually followed .by: the expulsion of considerable quantities of the preservative,

and the'quantity expelled being difficult to d measure, the accuracy of the process is lost, it being then guite impossible to determine the quantity 0 liquid remaining in the Wood. ow pressure gas or air is quite as effectual as the higher pressures in dlsseminating the liquid in the wood and when relieved escapes at such low velocity that its force is less. than the adhesion between the films of liquid and the cell walls, therefore, noloss or disturbance of the liquid films follows the removal of the wood from the cylinder.

After treatment with the compressed air, as above described, the wood is ready for use and the door of the cylinder being opened, the car is removed therefrom, markin the end of the process.

aving thus described my invention, I claim as new and desire to secure by Letters Patent:

1. The herein described improvement inthe art of preserving wood that consists in first exhausting the gaseous content of the wood, then immersing the wood in preservative liquid, then by pressure upon the liquid drivin the requisite quantity thereof nto the cel s and pores of the wood, then removing) the surplus liquid fromthe wood, then su jecting the partially impregnated wood to the action of compressed gas, thereby driving the charge'of liquid further into the wood and then removing the gas pressure, sub- 2. The herein described improvement in the art of preserving wood, that consists in causing a vacuum in the load by exhausting the gaseous content thereof, then immersing the Wood in non-aqueous preservative liquid,

and by pressure thereon driving the sameinto the outer pores and cells of the Wood until the re uisite quantity of liquid is lod ed therein; t en withdrawing the surplus liquid from the wood; then subjecting the wood to the action of low tem erature gas at relatively low pressure, unt' substantially gaseous equilibrium is established in the wood and then restoring the wood to atmospheric pressure, substantially as described.

3. The herein described improvement in the art of preserving Wood that consists in placing the wood in a closed vessel then exausting the gaseous contentof the vessel and of the wood until gaseous equilibrium at less than atmospheric pressure is established within the pores and cells of the wood; then subjecting thewood to pressure of preservative liquid at approximately atmospheric the iquid in the outer ores and cells of the wood without material y heating the wood;

then drawing off the surplus liquid then sub- Within the vessel, to

jecting the wood, still the action of gaseous pressure until gaseous equilibrium at substantially such ressure is established throu bout the 'WOO' thereby isseminating the iquid in the cells and pores of the woodand then relieving the pressure of gas and removing the wood from the vessel, substantially as described.

4, The herein described improvement in the art of preserving seasoned Wood that consists in creating a vacuum in and throughout the cells and pores of the wood, then immersing the wood in preservative liquid and by pressure upon the liquid driving the requisite quantity thereof into the outer cells and pores of the wood, then removing the surplus iquid, then subjecting the wood to the action of compressed as, thereby disseminat: ing the liquid througiout said cells and pores and then permitting the atmospheric pressure wit stantially as described.

5. The herein described improvement in the art of preserving wood that consists in placing the wood to be treated in a closed vesse sel and from the wood therein until a substantial vacuum is obtained throu bout the cells and ores of the wood; then ling the vessel wit Warm, non-aqueous preservative liquid, then exerting pressure upon the li uid until the re uisite quantity thereof is 10' ed in the woo then drawing ofi' the surp us liquid; then fillin the vessel with air under given pressure an maintaining said pressure until equilibrium is established throughout the wood, thereby disseminating said uantity of liquid in the pores and cells 0 the uiet restoration of in the wood, subwood, then relieving the air pressure and the art of preserving wood that consists in first creating a vacuum within the cells and pores of the wood, then, without materially reducin the said vacuum, in ecting into the then exhausting the air from said ves-' outer ce ls and pores of the wood a uantity of non-aqueous preservative liquid, t on draining the surplus liquid from the wood, then distributing the remaining liquid througheeaeeo out the cellular structure by external air 1 In testimony whereof, I have hereunto set pressure assisted by the vacuum within the my hand, this 11th day of May, 1908, in the wood, mean time keeping the preservative in presence of two subscribing witnesses. a liquid state by maintaining the tempera- WALTER BUEHLER.

5 ture thereof, and then reducing, to normal, Witnesses:

both the temperature of the wood and the CHARLES GILBERT HAWLEY, pressure therein, substantially as described. l JOHN R. LEFEVRE. 

